The specifications set out by The 3rd Generation Partnership Project (3GPP) define the operation of mobile voice and data services within a telecommunications network.
In a GSM mobile network, the subscriber is identified by his unique International Mobile Subscriber Identity (IMSI). The IMSI is stored on the subscriber's SIM card which is typically transportable and able to be removed and re-inserted into other mobile devices. The subscriber's phone number is known as the MSISDN. The combination of IMSI and MSISDN is held in a database maintained by the network operator known as the Home Location Register (HLR).
The General Packet Radio Service (GPRS) is a technology used in mobile networks to carry Internet Protocol (IP) packets across the network.
The roles of the Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN) are well defined in the 3GPP specifications and are familiar to persons skilled in the art. The term “3GPP specification” covers all GSM (including GPRS and EDGE), W-CDMA and LTE (including LTE-Advanced) specifications. The following terms are also used to describe networks using the 3G specifications: UTRAN, UMTS (in Europe) and FOMA (in Japan). Revised versions of these specifications are produced up to four times a year following the quarterly TSG plenary meetings and are publicly available for download at www.3GPP.org/specifications. All 3GPP specifications from the years 2000 through 2011 are hereby incorporated by reference in their entireties.
The GGSN is responsible for the interworking between the mobile GPRS network and external packet switched networks such as the Internet. Each SGSN is responsible for the delivery of data packets from and to the mobile stations within the geographical service area for which it is responsible.
GPRS tunneling protocol (GTP) is the protocol that allows end users of a GSM or WCDMA network to move from place to place while continuing to connect to the Internet. GTP carries the subscriber's data from the subscriber's current SGSN to the GGSN that is handling the subscriber's session. GTP data is transmitted in the form of Protocol Data Units (PDUs), otherwise known as G-PDUs.
When the mobile station wants to use GPRS, it must first attach and then activate a packet data protocol (PDP) context (“PDP context”). The PDP context is a data structure established on both the SGSN and the GGSN representing the subscriber's GPRS session information.
The Charging Gateway Function (CGF) is responsible for handling billing of the data packets consumed by the subscribers. The CGF listens to GTP messages sent by the GGSNs and SGSNs. The GTP messages contain Call Detail Records (also known as Call Data Records or CDRs) that are ultimately used to bill the subscribers. The information carried in the CDRs typically includes data session activation/deactivation times and the quantity of data that the subscriber has consumed.
Waller discloses a method and system for allowing subscribers who cannot afford to purchase their own mobile phone to borrow a mobile and make and receive calls and send/receive Short Message Service (SMS) messages using their own prepaid account. The service makes use of USSD (Unstructured Supplementary Service Data) commands to activate and deactivate the shared account and to access the various mobile services (such as placing and receiving calls, checking for missed calls and voicemails, and sending and receiving SMS messages). The method and system described herein further extends Waller's application with the additional benefit that the user is able to use mobile data services, such as browsing the Internet, on the borrowed mobile device using his own private account.
While examples of providing certain mobile services with a virtual number are disclosed in Ahn, what makes the method and system in the present application unique from Ahn is at least the ability to enable shared usage of mobile data services from a mobile device using a virtual IMSI.
In another invention, Thomas discloses the ability to enable shared data access, by enabling mobile data on a first device and setting up said first device to act as a point of presence in a network so that a second device may connect to the point of presence. Thomas' invention however, requires that the two devices to be connected to each other via a RF (radio frequency) interface.